Electric heater



S. l. PHELPS.

.ELECTRIC HEATER.

APPLICATION FILED IIIAII. 24. 1919. IIENEwED FEB. 1.1922.

1,432,491 Patented Oct. 17, 1922.

2 SHEETS-SHEET I.

S. I. PHELPS.

Y ELECTRIC HEATER. APPLgcATloN FILED MAR. 24, 1919. RENEWED FEB. 1.1922.`

1,432,491 Patented Oct. 17, 1922.

2 SHEETS-SHEET 2.

Patented Oct. 17, 1922.

UNITED STATES PATENT OFFICE.

SEBRING I. PHELPS, 0F ROCKFORD, ILLINOIS.

ELECTRIC HEATER.

To a'wio/m. if may conce/"n:

Be it known that I, SEBRING I. PHEIiPs, a citizen of the United States of America. anda resident of Rockford. in the county of IVinHebago and State of Illinois. have invented certain new and useful vImprovements in Electric Heaters, of which the following is a specification.

In the construction of electric heaters, it is the aim to produce as high a heat as possible with a view to equalizing the effectiveness of gas or other flame stoves. In seeking this end, two limitations are encountered which in the past have made it impossible to attain the desired end with practical constructions. One of these limitations is the area within which the heat can be practically generated and the other is the maximum capacity ot' the resistance material which can be placed within such area.

The reason for the first of these limitations is that it is advisable, i'f not necessary, to generate the heat within the diameter of the utensils which generally are to be used. In most instances these are from 6 to 8 inches in diameter. Thus, in an electric heater for general household use, it would be a waste of energy to heat an area larger than about 8 inches 1n diameter. Ot' course, when larger utensils are to be used, a correspondingly large heater could be provided. but even then its size would be limited to the average size of the utensils with which it was to be used. Being thus limited in size,only a certain amount of resistance material can be made use of within the available space, the amount being dependent upon the character of resistance material and the manner'of its use.

At present, practically all of the resistance material used is in the form of a small ribbon or wire of special metallic composition which is either wound on a sheet or block of insulating material, such as asbestos or mica, or suspended between or upon insulating members. It is recognized that a piece of this wire or ribbon of a given length and a given size will produce a certain maximum amount of heat at a given voltage and remain intact. Of course, the length or size ot' the'ribbon may be increased or decreased for the purpose of varying the heat produced. However, any material decrease in length of a given size, al-

Serial No. 533,409.

though resulting in an increase in temperature, will also result in a destruction of the ribbon or wire. Since this maximum heat 1s not very creat.I it has not been possible with the metliods heretofore adopted to produce a suliciently high heat to satisfactorily compete with gas or other flame stoves, and where 1n the past it has been attempted to attain the very highest heat of which the resistance material used was capable, the life of the resistance material has been found to be comparativel short, requiring frequent renewals or replacements, the expense and annoyance of which have restricted a more general use of electric heaters.

The main objects of this invention, therefore, are t0 provide an improved form of electric heater capable of producing a very high temperature with practically little or no danger of deterioration or destruction of the resistance material; to provide an improved construction and arrangement of a plurality of separately formed heating unit-s, each of which is adapted to operate at a comparatively low heat, and which are mounted relatively of each other so as to constitute a single heating element; to provide improved means for connecting said separately formed units in circuit with a source of electricity whereby various degrees of heat may be produced in said element; and to provide an improved heater of this kind wherein the several units are instantly removable and interchangeable and one or more may be removed or changed without interfering with the remaining ones. and the cutting out of one unit in no way affects the use of the others.

An illustrative embodiment of this invention is shown in the accompanying drawings. in which 95 Fig. 1 is a perspective view of one form of electric heater constructed in accordance with this invention.

`Fig. 2 is'an enlarged sectional elevation taken on the line 2 2 of Fig. 1. 100

Fig. 3 is a fragmentary detail illustrating an arrangement of contact members on the supporting frame.

Fig. 4 is an enlarged fragmentary sectional detail illustrating the construction and arrangement of a set of coacting contact members, the view being taken on the plane of the line 4-4 of Fig. 3f

Fig. .5 is a similar view taken on the line 5-5 ot' Fig. 3.

["ig. (i is a detail showing the manner in which one oi the units is iliade up.

Fig. T is a perspective view ot' a heater showing another arrangement ot the units.

Fig. S is a top plan ot the same.

Fig. 0 is a perspective view. partly in section. of one ot' the units used in the form shown in Fig. 7.

ln tht` past. there has been no practical method devised whereby more than two 0r vthree sections ot resistance material could be used in a single heating element. and these have been incapable of producing the desired results. either because the attempt to obtain a high heat from two or three such windings has resulted in a short life of the resistance material, or because the attempt to make the resistance material last a reasonable length of time has resulted in insulticient heat to enable competition with flame stoves. Accordingly. the Fundamental idea of this invention is to provide a number of separately constructed units each adapted to produce a comparatively loW heat and adapted to be assembled relative to each other so as to provide a single heating element, whereupon the low heat of each of the several units combines to produce a comparatively high temperature over the entire element. The maximum temperature obtainable trom such a heating element depends upon the. number of units within a given area and the temperature of each individual unit.

lxperience has shown that practically the highest heat obtainable from a single winding or unit is that produced by about 350 watts of current. Thus. by the methods heretofore used in constructing heaters. the highest temperature obtainable has been that Jfrom two or three` windings or units, which is substantially what 700 to 1000 watts of energy will produce. However, to obtain even such a heat, the resistance has been used to its capacity. and its usefulness has conlsequently been short-lived. On the other hand. it has been Found that if the resistalice is used at a lower wattage, for example, .250 watts. its usefulness is long-lived, and if to 1Q such units are assembled together in a lsingle element, it is possible to produce a wattage in said element of from 1500 to 3000 watts with a correspondingly high temperaf ture.

ln the modification shown in Fig. 1, the units 1 are sector-shaped, whereas in the modification shown in Fig. 7, they are oblong. In either case. each unit comprises substantially a strip of resistance wire or ribbon Q wound on a sheet of insulating material 3 which is placed between two other sheets of insulating material 4 and then encased in a metal envelope. The metal 'envelope consists of two plates 5 and 5.1, having the edges of one bent over the other. rllhe ends of the resistance ribbon or wire 2 are properly insulated and brought out through the metal case and connected to contact members 6 which are arranged to tit in the contact members 7 on the supporting frame 8 and connected to conductors 9.

The conductors 9 are three in number, and are herein shown to be concentrically arranged upon and connected to the underside of the frame 8. The contacts 7 are arranged in pairs, as indicated in Figs. 3 and 8, one of each pair being connected to the middle wire and the other of each pair being connected either to the inside or the outside conductor 9. Thus, part of the contacts 7 are connected in onev circuit. constituting the middle conductor and outside conductor, and the others are connected in another circuit comprising the middle conductor and the inside conductor. The conductors 9 are connected to a switch 11 supported on the frame 8, from whence the conductor 11 leads to a source of electricity. The switch 11 is of the usual multiple-heat type, whereby it is possible to place the several units 1 1n circuit with the source of electricity, so as to provide several different degrees of heat over the face of the element.

1n the embodiment shown in Fig. 1, six sector-shaped units are arranged on the frame 8 and the contacts 6 are secured at the outer corners thereof, as more clearly indicated in Fig. 3. At one corner the contact member 6 is fixed so as to alwaysengage the contact 7 connected to the middle'conductor 9 (F ig. 4), whereas the contact at the other corner is arranged sothat"` it mayy be turned to engage the contacts 7 connected to either the outside or inside conductor 9. as indicated in Fig. 5. It is therefore possible to construct the units 1 all in the same manner, and t one to any position on the frame, simply by turning the contact member 6, at said other corner, to engage one or the other of the contact members 7.'

In the modification shown in Fig. 7, the contact members 6 are arranged at opposite ends and near diagonally opposite corners. At one end, the contact 6 is arranged to engage the Contact 7 which connects with the middle conductor, and the contact 6 at the other end is arranged sojasto be shifted to engage the contacts 7 connected with either the outside or the inside Wire. This makes it possible for the units 1 in this particular modification to be constructed so as` to be interchangeable in pairs `on opposite sides of the main diameter of the frame.

The foregoing arrangementof the contact members 6 and 7 permits the units 1 to be arranged in place by placing the respective contacts in engagement with each other. Being thus arranged in parallel, each unit is independent of the others to the extent that it one burns out or is removed` the operation of the others is not interfered with. Furthermore. this arrangement of the units makes it possible tor a unit to be replaced or exchanged with another while th heater is in operation.

Although but two specific embodiments of this invention have been herein shown and described it will be understood that still other modifications may be provided and that numerous details ot' the modifications here shown may be altered or omitted without departing from the spirit of this invention as defined by the following claims.

I claim y l. A culinary electric heater comprising a frame. a plurality ot' separately constructed flat heating units arranged to fit flat on said frame. in the same horizontal plane so as to form a substantial. circular heating element and adapted to support a culinary utensil` with the bottom thereof in direct contact with the face ot' each of said units, each of said heating units including a resistance winding constructed to operate at a comparatively low wattage, and electric conductors on said frame connecting all of said heating units in parallel with each other and with a source of electricity.

2. A culinary electric heater comprising a frame. a plurality of separately constructed fiat segment shaped heating units arranged to fit side by side in substantially the same plane` so as to form al substantially circular heating element adapted to support a culinary utensil with the bottom thereof in direct contact with the t'ace ot' each ot' said units, each of said units including a resistance winding constructed to operate at a comparatively low wattage, and electric con ductors on said frame connecting all ot' said heating units in parallel with each other and with a source otelectricity.

3. An electric heater comprising a frame. a pluraltiy of contact members arranged thereon in sets, separately constructed units each provided with a complementary set of contact members. said units being adapted to have the contact members thereonl engage the respective contact members on said frame and thereby support said units in assembled relation on said frame so as to form a single heating element, and conductors connected with said sets of contacts on said frame so as to connect certain ot' said units in one circuit and certain other of said units in another circuit.

4. An electric heater comprising a frameA` a plurality of contact membersarranged thereon in sets. separately constructed units each provided with a complementary set of contact members. said units being adapted to have the contact members thereon engage the respective contact members on said frame and thereby support said units in assembled relation on saidframe so as to form a single heating element. conductors connected with said sets of contacts on said frame so as to connect certain of said units in one circuit and certain other of said units in another circuit. and a switch connected to said conductors whereby said different circuits may be variously placed in and out ot' connection with a source of electricity substantially as described.

5. An electric heater comprising a frame. a plurality of electrical conductors arranged on said frame and each provided with its respective contacts. and a plurality of separately constructed heating units each provided with a pair of electrical contacts, said units being arranged side by side on said frame and having contacts on certain of said units engaged with the contacts of certain two of said conductors. and having the contacts of the remaining units engaged with contacts ot' certain other two of said conductors whereby said certain units are connected in parallel with each other in one circuit and said remaining units are connected in parallel with each other in another circuit.

6. An electric heater comprising a frame. a plurality of electrical conductors arranged on said trame and each provided with its respective contacts, a plurality of separately constructed heating units each `provided with a pair of electrical contacts, said units beiner arranged side by side on said frame and laying contacts on certain of said units engaged with the contacts of certain two of said conductors, and having the contacts of the remaining units engaged with contacts of certain other two of said conductors whereby said certain units are connected in parallel wit-h each other in one circuit and said remaining units are connected in parallel with each other 'n nother circuit, and a switch connected t aid conductors whereby said two circuits may be variously placed in and out of connection with a source of electricity, substantially as described.

7- An electric heater comprising a sup! porting frame. a plurality of separately constructed heating units arranged on said frame side by side, a multiple heat switch, and three electrical conductors leading from said switch, one of said conductors being connected to one terminal of each of said heating units, a. second of said conductors being connected to the other terminal of a part of said units, and the third conductor being connected tothe other terminal of the remaining units, wherebyy said units are connected in two groups with the units of each group connected `in parallel with each other.

8. An electric heater comprising a supporting frame, a plurality of separately constructed heating units arranged on said frame side by side, a multiple heat switch, and three elec.-

tiical conductors leading from Said switch,

vone of said conductors being connected to one terminal of euch of said heating units, u second ot said conductors being connected to the other terminal of substantially onehalf of said units, and the third conductor being connected to the other terminal of the SEBRING I. PHELPS. 

